Maximum Noise Level Research Articles

Оценка уровней шума в Санкт-Петербургском метрополитене

Purpose: to assess the impact of noise levels in St. Petersburg metro cars. Identify what types of cars used on various metro lines. Determine what types of rolling stock cars used in the metro. Determine how much the service life of the cars affects the noise level in the car. Conduct measurements of noise levels inside the carriages of rolling stock of various types on various metro lines. Correlate the obtained values with the established requirements of SP 2.5.3650–20 “Sanitary rules for the operation of subways” with the values of maximum permissible noise levels in cars. Conduct an analysis of the level of noise impact on humans in the metro and identify possible measures to reduce the noise level in the metro. Methods: measurements of noise levels at various stations and trains were carried out by a special instrumental method, using a digital integrating meter and an Octave 110A sound spectrum analyzer of 1st accuracy class according to GOST R 53188.1. Results: measurements of noise levels carried out in various types of cars on various branches of the St. Petersburg metro. An analysis of the results of field measurements of noise levels for equivalent and maximum levels in the metro shows that permissible noise levels are exceeded in the “Baltiets” car on the red metro line, in car 81-717/714 on the blue metro line; in car 81-717/714 on the purple metro line; in car 81-556.2/557.2/558.2 “Neva” on the green metro line. Practical significance: identification of the obtained data show necessary measures to reduce noise in the metro. Installation of sound-absorbing materials at stations and on trains. Replacing old trains with newer ones.

Indices of vertebral vein discirculation in workers in noise occupaions

Introduction. Occupational sensorineural hearing loss (OSNHL) is a gradual bilateral hearing loss developing over several years as a result of exposure to constant or non-constant noise (mainly high-frequency) at the workplace as one of the main causes in etiology, researchers name a violation of blood supply and vascular stenosis. The purpose of the study is to evaluate the indices of venous dyscirculation under the influence of industrial noise at the early stages of the development of OSNHL. Materials and methods. Twenty two male patients who have been working in conditions exceeding the maximum permissible noise levels for more than 5 years were examined, and the comparison group included 29 healthy male volunteers from 27 to 55 years old who do not work in the production sector. All the subjects were examined by an otorhinolaryngologist, a neurologist, and a therapist. Audiometry was performed on two axes for everyone. Air and bone conduction were performed separately for each ear. All patients underwent a triplex scan of the arteries and veins of the neck and brain in the supine and standing positions. Results. In comparison with the control group of healthy volunteers who did not work in industrial noise conditions, workers in noise occupations had a significant increase in blood flow, which averaged 25.2 cm/sec. When measuring the diameters of the vertebral veins, a tendency to vasodilation was revealed. Limitations. The limitation was the small sample size, due to the low patient turnover at the preclinical stage. Conclusion. The complex effect of noise on the body leads to changes in the wall of the venous network, a violation of venous outflow and can manifest itself not only with clinical complaints, but also in the form of episodic dizziness, cephalgia, which in turn can worsen the course of the development of OSNHL. It is necessary to perform ultrasound dopplerography of the neck veins for all workers of noise occupations at the preclinical stage to assess the risk of OSNHL occurrence.

Males miss and females forgo: Auditory masking from vessel noise impairs foraging efficiency and success in killer whales.

Understanding how the environment mediates an organism's ability to meet basic survival requirements is a fundamental goal of ecology. Vessel noise is a global threat to marine ecosystems and is increasing in intensity and spatiotemporal extent due to growth in shipping coupled with physical changes to ocean soundscapes from ocean warming and acidification. Odontocetes rely on biosonar to forage, yet determining the consequences of vessel noise on foraging has been limited by the challenges of observing underwater foraging outcomes and measuring noise levels received by individuals. To address these challenges, we leveraged a unique acoustic and movement dataset from 25 animal-borne biologging tags temporarily attached to individuals from two populations of fish-eating killer whales (Orcinus orca) in highly transited coastal waters to (1) test for the effects of vessel noise on foraging behaviors-searching (slow-click echolocation), pursuit (buzzes), and capture and (2) investigate the mechanism of interference. For every 1 dB increase in maximum noise level, there was a 4% increase in the odds of searching for prey by both sexes, a 58% decrease in the odds of pursuit by females and a 12.5% decrease in the odds of prey capture by both sexes. Moreover, all but one deep (≥75 m) foraging attempt with noise ≥110 dB re 1 μPa (15-45 kHz band; n = 6 dives by n = 4 whales) resulted in failed prey capture. These responses are consistent with an auditory masking mechanism. Our findings demonstrate the effects of vessel noise across multiple phases of odontocete foraging, underscoring the importance of managing anthropogenic inputs into soundscapes to achieve conservation objectives for acoustically sensitive species. While the timescales for recovering depleted prey species may span decades, these findings suggest that complementary actions to reduce ocean noise in the short term offer a critical pathway for recovering odontocete foraging opportunities.

Robust-mv-M-LSTM-CI: Robust Energy Consumption Forecasting in Commercial Buildings during the COVID-19 Pandemic

The digitalization of the global landscape of electricity consumption, combined with the impact of the pandemic and the implementation of lockdown measures, has required the development of a precise forecast of energy consumption to optimize the management of energy resources, particularly in pandemic contexts. To address this, this research introduces a novel forecasting model, the robust multivariate multilayered long- and short-term memory model with knowledge injection (Robust-mv-M-LSTM-CI), to improve the accuracy of forecasting models under uncertain conditions. This innovative model extends the capabilities of mv-M-LSTM-CI by incorporating an additional branch to extract energy consumption from adversarial noise. The experiment results show that Robust-mv-M-LSTM-CI demonstrates substantial improvements over mv-M-LSTM-CI and other models with adversarial training: multivariate multilayered long short-term memory (adv-M-LSTM), long short-term memory (adv-LSTM), bidirectional long short-term memory (adv-Bi-LSTM), and linear regression (adv-LR). The maximum noise level from the adversarial examples is 0.005. On average, across three datasets, the proposed model improves about 24.01% in mean percentage absolute error (MPAE), 18.43% in normalized root mean square error (NRMSE), and 8.53% in R2 over mv-M-LSTM-CI. In addition, the proposed model outperforms “adv-” models with MPAE improvements ranging from 35.74% to 89.80% across the datasets. In terms of NRMSE, improvements range from 36.76% to 80.00%. Furthermore, Robust-mv-M-LSTM-CI achieves remarkable improvements in the R2 score, ranging from 17.35% to 119.63%. The results indicate that the proposed model enhances overall accuracy while effectively mitigating the potential reduction in accuracy often associated with adversarial training models. By incorporating adversarial noise and COVID-19 case data, the proposed model demonstrates improved accuracy and robustness in forecasting energy consumption under uncertain conditions. This enhanced predictive capability will enable energy managers and policymakers to better anticipate and respond to fluctuations in energy demand during pandemics, ensuring more resilient and efficient energy systems.

A directivity correction for accurate semi-empirical wind turbine noise prediction

Public acceptance of wind farms is a significant challenge in the development of wind energy. The acoustic impact generated by wind turbines is a common concern among local residents. The primary noise source in wind turbines is generated by aerodynamics. Atmospheric turbulence reaching the blade leading edge or turbulent boundary layer passing the trailing edge produce the main aeroacoustic sources. The noise generated by these mechanisms is commonly predicted by means of semi-empirical models, which do not demonstrate great reliability when compared to acoustic measurements. This paper presents a correction to the directivity of airfoil noise radiation, resulting in improved sound pressure levels on the ground plane surrounding a wind turbine. This improvement is achieved without requiring any additional computational effort. The sound pressure levels perceived on the ground plane are known to have asymmetrical shape. Maximum noise levels correspond to observers directly in the upwind and downwind locations, whereas the minimum levels belong to the positions close to the rotor plane. Said asymmetrical shape is not represented in the semi-empirical models. The proposed correction takes into consideration the airfoil thickness in the radiation directivity equations, resulting in the expected asymmetrical shape of noise footprints on the ground plane around a wind turbine. The correction was found to not affect the accuracy of the spectrum predicted by the semi-empirical models when compared to dedicated field measurements under the standard IEC 61400-11 procedure. When implementing the proposed correction, the virtual NREL 5 MW wind turbine’s published noise footprints, which were originally calculated using computationally expensive methods, are accurately reproduced.

Measurement and prediction of road traffic noise at different floor levels of buildings in a mid-sized Indian city

It is widely accepted that residents of high-rise buildings located beside roads are inevitably exposed to significant levels of noise pollution due to traffic operation. This study aims to unveil crucial insights into the dynamic fluctuations of noise levels within the vertical dimensions of high-rise buildings nestled amidst the bustling streets of mid-sized Indian cities where heterogeneous traffic is under operation. Two cycles of data were collected on all floors for hourly duration on the façade line for two high-rise buildings. Traffic volume, speed, distance of the building from centre of the carriageway and honking were used to develop models for Leq and L10 using Artificial Neural Network (ANN). The R2 values obtained for Leq and L10 were 0.93 and 0.90, respectively indicating the efficacy of the models in predicting noise level at all floors. Results show that the sound level rises to a certain height of the building and then begins to decrease. Floor level 3, 4, 5 and 6 (height approx. 8.4–21 m) had the maximum noise level compared to the other floors, while the 1st and floor level above 10 were quieter floors. Frequency analysis reveals that buildings closer to roadways experience dominant honking noise, particularly at 3.15 kHz, whereas traffic noise prevails at frequencies up to 200 Hz. This work has the novelty of addressing the impact of heterogeneous traffic noise at various floor levels of Varanasi mid-sized city which has narrow carriageway. Such a traffic has prominence of honking which is modelled perhaps for the first time. The outcome of this research has importance in urban planning and formulating legislations.

Hydrogeochemical characteristics and air quality risks associated with gold mining operations in Egypt using geochemical modeling and risk indices

The success of industrial operations depends on the effective identification, appraisal, and mitigation of possible hazards and associated environmental concerns. This report provides a complete review of environmental management techniques at the Sukari Gold Mine (SGM), located in the southeastern desert of Egypt. Extensive environmental measurements were taken to assess air and water quality, identify hazards, and analyze risks on the SGM premises. Air quality and noise intensity levels were measured at 39 places around the mine's working region. The findings found noncompliance with the Egyptian Environmental Law's (EEL4/94) noise exposure limitations, with the Power Generator House having the maximum noise levels at 107 dB. Remedial measures such as personal protective equipment (PPE) and exposure limit reduction strategies are being considered to address elevated noise levels. Measurements of particulate matter (PM10) and noxious gases (e.g., CO, SO2, NO2, HCN, and NH3) were conducted in workplace and ambient environments. Elevated PM10 concentrations were particularly concerning in underground regions, forcing the deployment of water depression techniques and improved PPE measures. While gas emissions from most activities remained under regulatory limits, select zones showed hydrogen cyanide (HCN) levels that exceeded permitted thresholds, necessitating specific control actions. Using hazard index (HI) and risk rating assessments, this study found different risk profiles across SGM's workplaces, focusing on high-risk regions for focused intervention. Additionally, a water assessment near a Tailing Storage Facility (TSF) was conducted to monitor the impact of mining activities on groundwater quality. The study revealed that groundwater in the region belongs to the Na–K–Cl–SO4 and Ca–Mg–Cl–SO4 water classes, with potential degradation attributed to high mineralization processes induced by aquifer materials and seawater intrusion. The findings underscore the importance of ongoing monitoring, control measures, and implementation of programs to ensure environmental sustainability and minimize risks associated with mining activities in the Sukari Gold Mines. This research highlights the imperative of continuous monitoring, proactive control measures, and the implementation of environmental initiatives to ensure the sustainability of mining operations within the Sukari Gold Mines.

Climatic Variations and Indoor Environmental Quality Performance of Houses in Selected Cities in Oyo State, Nigeria

Understanding how climatic variations influence Indoor Environmental Quality (IEQ) becomes crucial for designing sustainable and comfortable living spaces in this specific region. This study therefore investigates the effect of climatic variations on IEQ performance of houses in selected cities within Oyo State, Nigeria. The types of data collected for the study were numeric and ordinal. The numeric data of air temperature, relative humidity, air velocity and noise level, were gotten through objective measurements and IEQ through IEQ Calculator. The ordinal data were gotten through observation and questionnaire. Control Potential Zone technique on psychometric chat was used to analyze climate of Ibadan, Ogbomoso and Kisi. The physical measurements were conducted in the living, bedroom and kitchen spaces of the sampled houses in the low, medium and high residential density zones of the selected cities. A sample size of 581 houses from 3,490 were selected across each of the three residential density zones in the selected cities. The indoor temperature and relative humidity in the three cities were higher during the afternoon period with average thermal stress index of 39.40C, 36.90C and 38.40C respectively for Ibadan, Ogbomoso and Kisi respectively. None of the spaces satisfied the effective indoor ventilation comfort criteria of between 0.5m/s -1.5 m/s. All the spaces except the bedroom space in the compound impluvium house type satisfied the illumination range of between 50 – 60 lux. The maximum indoor noise level during the morning, afternoon and evening periods in study area were 58db, 59db and 58db respectively. Result from the IEQ calculator indicated that majority of the houses (83.6%) were star 2 in the IEQ performance. The implication was that these houses were below average in terms of IEQ performance.

Do Surgical Smoke Evacuators Increase the Risk of Hearing Loss for Operative Personnel During Routine Adenotonsillectomy Surgery?

Aerosol mitigation equipment implemented due to COVID-19has increased noise levels in the operating room (OR) during otolaryngological procedures. Intraoperative sound levels may potentially place personnel at risk for occupational hearing loss. This study hypothesized that cumulative intraoperative noise exposures with aerosol mitigation equipment exceed recommended occupational noise exposure levels. Sound levels generated by the surgical smoke evacuator (SSE) during adenotonsillectomy were measured using a sound level meter and compared to surgery without SSE. Thirteen adenotonsillectomy surgeries were recorded. Mean sound levels with the SSE were greater than the control (72 ± 3 A-weighted decibels (dBA) vs. 68 ± 2 dBA; p=0.015). Maximum noise levels during surgery with SSE reached 82 ± 3 dBA. Surgeons performing adenotonsillectomy with aerosol mitigation equipment are exposed to significant noise levels. Intraoperative sound levels exceeded international standards for work requiring concentration. Innovation is needed to reduce cumulative OR noise exposures.

Numerical study of the influence of quadrotor blade parameters on aerodynamic noise generation

The aim of this paper is to study the effect of variation of the parameters of a small-sized quadrotor blade on the level of aerodynamic noise and its frequency spectrum. There is a certain discrepancy between the calculated and experimental data available today. The reason for this is that the study of quadrotor rotor noise is carried out using various theoretical models that do not consider certain factors of sound generation or additional artificial sound sources, which result in an overestimated noise level. Therefore, there is a need for an accurate model, the calculation of which more closely matches the experimental data. In the paper below, an aerodynamic noise model is proposed to study the noise of a quadrocopter blade, which considers the non-stationarity and three-dimensionality of the sound generation and propagation process. The research methods are based on the numerical calculation of the characteristics of the near and far sound fields in the potential approximation: pressure coefficient, sound pressure level, and spectrum of the generated sound. The main parameters that were varied during numerical calculations were the rotor speed of the quadrotor, angle of attack, torsion angle, and blade position in the plane of rotation. The NASA parabolic profile was used as the test profile. Results and conclusions. The results of numerical calculations in the near field revealed three areas of sound generation above the blade surface. The first region, which is more unstable, is caused by blade torsion. The other two sound generation areas are smoothly distributed along the blade’s swing, and the pressure change level in each of them doubles. The level of generated aerodynamic noise is largely dependent on the blade speed and the distance from the blade at which the noise is calculated. The angle of attack and blade pitch have a smaller effect on the generated noise level, and in the far field, they have almost no effect on the maximum noise level. The dependence of noise on the distance to the blade, as well as the blade parameters, which were chosen similar to those studied by other authors, showed a fairly good agreement with the calculations of these authors and with experimental studies. Because of aerodynamic calculations and noise generation around the quadrotor blade using ANSYS software, it was found that sound vibrations occur during the flow around the blade tip, with a level of 120 dB in the immediate vicinity of the blade surface. Calculations using a 3D model of the propeller confirmed that the volume reached 80 dB at the nearest reference point, which closely matches the data from the calculation based on the potential model and the experimental data.

Numerical Prediction of Trailing Edge Noise at Low Reynolds Number with Modified Trailing Edges of a NACA 0015 Airfoil

Global concern about high noise levels in areas near airports and wind farms has generated interest from various groups due to factors such as potential health problems and dissatisfaction among the local community. To accommodate this worthwhile plan of further reducing overall noise levels, some researchers are working on lowering the contribution of trailing-edge noise. The original scientific contribution of this study lies on understanding the efficiency of various trailing edge designs such as baseline, serrations, comb and comb-serrated, across different angles of attack and Reynolds numbers, while also addressing the limitations of existing geometrical models for trailing edges. The study intends to examine the performance of these different configurations, with an emphasis on their effect on acoustic responses. By utilizing large-eddy simulation and applying the Ffowcs-Williams and Hawkings models for noise prediction, an investigation was conducted to assess the impact of these trailing edge configurations on radiated noise at a low Reynolds number of 1.6× 105. The numerical predictions of lift coefficient and surface pressure fluctuations are compared and validated with a published study and experimental data, showing satisfactory results. Further analysis of these study has demonstrated that prominent peaks at lower frequencies (<103) are observed, which are identified as the characteristic frequencies. Moreover, results showed irregular broadband noise (300 - 600 Hz) with increased noise and shifting peak frequency as angle of attack rose. The serrated trailing edge design notably reduced noise levels by roughly 21 dB, especially for low frequencies. Comb-serration increased high-frequency noise by about 9 dB for angles of attack at 0, -1, and -20, and achieved a reduction of approximately 9 dB for angles of attack at 1 and 20. On the other hand, the directivity pattern showed that the maximum noise level is observed to predominantly radiate at an azimuth angle of around 90 degrees for all the cases, ranging from 900 to 2700, indicating that the majority of the source's acoustic energy is being emitted on the suction and pressure sides of the airfoil.

Smartphone-Facilitated In-Situ Hearing Aid Audiometry for Community-Based Hearing Testing.

Hearing loss prevalence is increasing, with an estimated 2.5 billion people affected globally by 2050. Scalable service delivery models using innovative technologies and task-shifting are World Health Organization priorities to improve access to hearing care, particularly in low- and middle-income countries. Smartphone-facilitated audiometry in the community using hearing aids covered by noise-attenuating ear cups ("in-situ") could support more accessible hearing care when provided by less trained individuals such as community health workers (CHWs). This study aimed to determine the validity of this method for potential hearing aid fitting. Study objectives included determining the maximum permissible ambient noise level (MPANL), inter-device reliability, clinical threshold accuracy, reliability, and performance in real-world settings. Experiment 1: 15 normal-hearing adult participants were evaluated to determine MPANLs for circumaural Peltor 3M earcups covering Lexie Lumen hearing aids with smartphone-facilitated in-situ audiometry. MPANLs were calculated by measuring the difference in attenuation between thresholds obtained with standard headphones and in-situ hearing aids. Experiment 2: Pure-tone frequency and intensity output of 14 same-model Lexie Lumen hearing aids were measured to determine inter-device reliability. Pure-tone stimuli were measured and analyzed to determine sound pressure levels in decibels and pure-tone frequency when connected to a test box 2cc coupler. Experiment 3: 85 adult participants were tested in a sound booth to determine the accuracy of automated in-situ pure-tone audiometry (PTA) compared to clinical PTA (500, 1000, 2000, 3000, 4000, 6000 Hz) facilitated by an audiologist. The first 39 participants were tested twice to determine test-retest reliability. Experiment 4: In a community setting, 144 adult participants were tested with automated in-situ audiometry facilitated by CHWs using a smartphone app. These participants were subsequently tested with automated mobile PTA (500, 1000, 2000, 4000 Hz). An additional 44 participants were tested twice to determine test-retest reliability. Experiment 1: MPANLs of the Peltor 3M earcup-covered hearing aids were higher than standard headphones across all frequencies, ranging from 24 to 47.3 dB SPL. Experiment 2: Inter-device performance reliability was high, with all inter-device differences across all intensities and frequencies less than 3 dB. Frequency output was consistent and differed less than 0.7% between devices. Experiments 3 and 4: 85.2% and 83.3% of automated in-situ audiometry thresholds were within 10 dB of thresholds obtained in the sound booth and in a community setting, respectively. Acceptable test-retest intraclass correlation coefficient (ICC) was evident across all thresholds obtained in a sound booth (ICC = 0.85 to 0.93) and in a community setting (ICC = 0.83 to 0.97). Smartphone-facilitated in-situ audiometry allows for reliable and valid community-based testing. A simple smartphone user interface and automated in-situ audiometry allow CHWs with minimal training to facilitate the testing. With the additional capability to program hearing aids via the smartphone after the initial test, this approach would have the potential to support widespread access to personalized hearing aid fittings facilitated by CHWs in low- and middle-income countries. This approach also supports self-fitting options based on in-situ thresholds, enabling testing and fitting via over the counter hearing aids.

Evaluation of Equivalent Noise Levels across Some Commercial Areas of Warri and Benin Metropolis in Nigeria

Globalisation has given rise to an increase in the amount of noise generated around us, such that man has adjusted to this increment without considering the possible risks associated with it. This study aims to measure the equivalent noise level in eighteen (18) locations in some commercial areas of Warri and Benin Metropolis in Nigeria using a noise level metre (Model: CEL-231). The assessment was done twice daily, during the day and at night. The results obtained revealed that the daytime equivalent noise level of both cities ranged from 48–68, 78–102 dBA for minimum and maximum noise levels, while the nighttime equivalent noise level ranged from 39–59, 59–83 dBA for minimum and maximum levels, respectively. It was observed that the daytime noise level values in some locations for both cities were higher than the nighttime values and also higher than the recommended standard noise quality description for daytime and nighttime duration as recommended by the World Health Organization (WHO) and some existing literature in Nigeria and across the globe. The reason for this noise level elevation is due to the activities of automobiles and tricycles plying the road incessantly, and again, these are major industrial cities with a lot of activities during the daytime. However, it can be recommended that those whose daily activities confine them to areas with unhealthy noise levels ensure at least 10 hours of recovery time in areas where the sound level is less than 65 dBA and also encourage the planting of trees in this vicinity

A compact multi-pixel superconducting nanowire single-photon detector array supporting gigabit space-to-ground communications.

Classical and quantum space-to-ground communications necessitate highly sensitive receivers capable of extracting information from modulated photons to extend the communication distance from near-earth orbits to deep space explorations. To achieve gigabit data rates while mitigating strong background noise photons and beam drift in a highly attenuated free-space channel, a comprehensive design of a multi-functional detector is indispensable. In this study, we present an innovative compact multi-pixel superconducting nanowire single-photon detector array that integrates near-unity detection efficiency (91.6%), high photon counting rate (1.61 Gcps), large dynamic range for resolving different photon numbers (1-24), and four-quadrant position sensing function all within one device. Furthermore, we have constructed a communication testbed to validate the advantages offered by such an architecture. Through 8-PPM (pulse position modulation) format communication experiments, we have achieved an impressive maximum data rate of 1.5 Gbps, demonstrating sensitivities surpassing previous benchmarks at respective speeds. By incorporating photon number information into error correction codes, the receiver can tolerate maximum background noise levels equivalent to 0.8 photons/slot at a data rate of 120 Mbps-showcasing a great potential for daylight operation scenarios. Additionally, preliminary beam tracking tests were conducted through open-loop scanning techniques, which revealed clear quantitative dependence indicating sensitivity variations based on beam location. Based on the device characterizations and communication results, we anticipate that this device architecture, along with its corresponding signal processing and coding techniques, will be applicable in future space-to-ground communication tasks.

Acoustic assessment of a novel visor concept with aerodynamic sealing for medical care

This paper presents the experimental acoustic assessment and optimization of a novel solid visor with aerodynamic sealing for medical care. This Personal Protective Equipment (PPE) ensures an effective aerodynamic sealing of the breathing zone thus reducing the risk of inhaling droplets and aerosols carrying a potential infectious agent. The PPE relies on an air curtain system that may generate considerable noise unsuitable for prolonged usage, so it is essential to investigate solutions to reduce the noise level. The main investigated sound descriptors were the A-weighted Noise Equivalent Level, the Third-Octave Frequency Distribution, and the Speech Intelligibility Index (SII), considering different solutions for air flow rate, tube diameter, thickness and insulation, configurations of the tube splitter and plenum, and the incorporation of physical barriers and a sound muffler. Through several optimizations, noise equivalent levels were reduced by 20 to 30 dBA for air flow rates of 15 to 30 l/min. The final prototype generates a maximum noise level of 45.2 dBA. The SII was improved from poor to excellent, with values close to 1 for all air flow rates considered. The impact on the speech was investigated and the results were also compared to those obtained with a surgical mask and a FFP2 respirator. This study shows the potential of employing different strategies to enhance the acoustic performance of personalized air-curtain protective devices.

Assessment and Optimization Strategies of Campus Sound Environment

A good sound environment is essential in creating a harmonious and peaceful campus, improving students’learning outcomes, promoting physical and mental health, and creating a green and healthy campus. This study investigated the impact of new buildings on existing ones by optimizing the spacing between new buildings and the sound insulation structure of building enclosures. The results indicated that building 4 was affected by the noise from new building 1 and its surroundings, with a maximum outdoor daytime noise level reaching 69 dB, and the indoor background noise level in the least favorable classroom was 43.73 dB, less than 45 dB, which was within the acceptable range. It is recommended that the sound insulation design be improved in the planning of new teaching buildings. Besides, the surrounding traffic conditions should be improved, and the usage time of sports facilities should be scheduled appropriately to prevent the noise from sporting activities from affecting the classroom activities. The findings of this study provide valuable references for future architectural acoustics design and campus planning, contributing to the creation of peaceful and comfortable campus environments.

Determining the impact of noise exposure of mining enterprises’ workers

This study investigated one of the main harmful factors at work, namely the impact of noise exposure on employees. The study was conducted in several stages. At the first stage, an on-site measurement was carried out using a calibrated sound level meter and a special smartphone application in the immediate vicinity of the ore grinding mill. It was found that the noise level is not constant. At the second stage, a mathematical dependence of the noise measurement results on the mill operating time was obtained to compare the measurement accuracy of the sound level meter and the app. As a result, it was determined that the application has sufficient accuracy compared to the calibrated instrument. The third stage resulted in the calculation of the risk of hearing loss for employees from noise exposure at workplaces based on the measurements of the calibrated sound level meter. The calculations showed that the level of this risk is high. At the fourth stage, personal protective equipment was selected using the relevant guidelines from NIOSH and EU-OSHA, as well as considering the results of field measurements, the maximum permissible noise level established by state sanitary standards, and the level of hearing loss risk.

Шумовое загрязнение территории многоэтажных жилых застроек города Ставрополя

The article provides measurement results and an assessment of the noise load on the territory of the «Perspektivny» and «Rossiysky» residential complexes in Stavropol. Noise measurements were carried out in the spring-summer and autumn-winter periods of 2022–2023. The measurement results are presented as average noise exposure levels. Based on the data obtained, a mathematical model of the propagation of noise from traffic flow during the deciduous and leafless period was built. To conduct a study and assess the noise load in a multistorey building on the territory of the South-Western district of Stavropol. The measurement of the noise load was carried out in accordance with GOST 23337-2014 “Noise. Methods for measuring noise in residential areas and in residential and public buildings”. To analyze and compare the data obtained with the maximum permissible value, SanPiN 1.2.3685-21 “Hygienic standards and requirements for ensuring the safety and (or) harmlessness of environmental factors for humans” was used. The measurement results revealed excess of maximum permissible noise level on the territory of the residential complex «Perspektivny» and «Rossiysky», and the houses within the residential complex «Perspektivny» suffer most from the proximity of the roadway and the absence or partial landscaping. Noise values were recorded near residential buildings in the range of 70 dBA. On the territory of the residential complex “Rossiysky”, high indicators are found on the sidewalk near the South-Western bypass. No excess of maximum permissible noise load level was noticed directly at the houses. The resulting mathematical model reflects the dependence of the noise level on the presence and absence of foliage and the density of traffic flow. Based on the data obtained, we can conclude that the residential complexes «Perspektivny» and «Rossiysky» are subject to significant noise pollution. This can be attributed to shortcomings in the planning of territory development and the increase in the number of vehicles.

Assessment of Noise Levels of Churches in the Kpone Katamanso Municipal Assembly in Ghana.

Different sound levels are encountered by pastors, ministers, and the whole congregation during church services, which may extend for hours, and also by people living close to these churches. This can have an adverse effect on their health. The maximum allowable noise level in worship places is 65 dB (A), according to the Ghana Standards Authority (GSA). The aim of the study was to quantify the noise pollution levels of the churches in Kpone Katamanso Municipal Assembly (KKMA) and assess the equivalent noise levels of the churches' indoor and outdoor spaces. This investigation is being conducted due to the high number of churches and the noise emanating from these churches in the Kpone Katamanso Municipality and the possible impact on human health. Thirty churches were chosen at random for the study; on Sundays between the hours of 7.30 and 12.0 pm, sound levels in churches were measured using a portable General Class 1 Meter type DSM403SD with a data logging system. MS Excel was used to evaluate the data and determine characteristics including noise exposure levels (NEL), background noise level (L 90), severe noise level (L 10), and equivalent noise level (L eq). The indoor equivalent noise level ranges from 74.5 dB (A) to 104.1 dB (A), and the outdoor equivalent noise level ranges from 52.6 dB (A) to 85.3 dB (A). All of the noise levels found indoors of the churches were greater than the 65 dB (A) safe allowable limit, putting the congregants and residents at risk for a variety of physiological and psychological problems.

Investigation on the time/frequency domain prediction model of radiation noise based on the source map

The main exterior noise sources of the high-speed train CRH380AM, such as pantograph and bogie, are studied by using the field test sound imaging data, and the equivalent point source spectrums are obtained here. Then, the prediction model of the exterior train noise is presented by using the moving point sound source radiation model in the time/frequency domain. The correctness and effectiveness of the model are verified by the field test data. The radiation contribution of local noise sources is analyzed by using this model, and the following conclusions are obtained: The largest noise sources are in the bogie areas, which provide the radiation contribution rate of about 80% when the train speed is above 300 km/h. The variation of the maximum radiation noise level can be ignored when the train formation or the pantograph lifting position is changed. The model can evaluate the radiated noise of similar vehicles quickly and accurately, which provides technical reference for acoustic optimization design of high-speed train.